Gas-driven liquid pump

ABSTRACT

A gas-driven liquid pump includes a gas source, a tank, a pumping pipe, at least one gas conveying pipe, and at least one liquid conveying pipe. The pumping pipe includes a gas input end, a liquid output end and a suction portion located between the gas input end and the liquid output end. An inner diameter of the pumping pipe gradually decreases from the gas input end to the suction portion, and the inner diameter of the pumping pipe gradually increases from the suction portion to the liquid output end. At least one gas conveying pipe is configured for connecting the gas source and the gas input end of the pumping pipe. One end of the liquid conveying pipe is connected to the tank, and another end is engaged with the suction portion of the pumping pipe.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to liquid pumps and, particularly, to a gas-driven liquid pump.

2. Description of Related Art

Gas-driven diaphragm pumps are widely used in industrial drainage systems. A typical gas-driven diaphragm pump includes a first working chamber, a second working chamber, a connection pole for connecting the first working chamber with the second working chamber. A first diaphragm is positioned in the first working chamber. A second diaphragm is positioned in the second working chamber. One end of the connection pole is connected to the first diaphragm, and another end of the connection pole is connected to the second diaphragm. The first diaphragm and the second diaphragm are synchronously driven, by the connection pole, in their corresponding working chamber. The pumping or draining process, of the air-driven diaphragm pump, can be performed by the synchronous action of the first and second diaphragm. This type of gas-driven diaphragm pumps can pump or drain a large volume of water, so gas-driven diaphragm pumps are often used in large-scale drainage systems. However, the gas-driven diaphragm pumps are complex in structure and large in size due to the size of the working chambers. Thus, a large space/area is required to function such gas-driven diaphragm pump.

However, some industry drainage systems need small-sized liquid pump to pump or drain water. Particularly, in a wetting process for making flexible printed circuit boards, a small quantity of water is sprayed on and wet the surface of the flexible printed circuit boards. In order to meet such requirement, a gas-driven liquid pumping apparatus having a small size is desired.

SUMMARY OF THE INVENTION

An embodiment of a gas-driven liquid pump includes a gas source, a tank, a pumping pipe, at least one gas conveying pipe, and at least one liquid conveying pipe. The pumping pipe includes a gas input end, a liquid output end and a suction portion located between the gas input end and the liquid output end. An inner diameter of the pumping pipe gradually decreases from the gas input end to the suction portion, and gradually increases from the suction portion to the liquid output end. At least one gas conveying pipe is configured for connecting the gas source and the gas input end of the pumping pipe. At least one liquid conveying pipe is configured for connecting the tank and the pumping pipe. One end of the liquid conveying pipe is connected to the tank, and another end is engaged with the suction portion of the pumping pipe.

Advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present gas-driven liquid pump can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present gas-driven liquid pump. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a schematic, isometric view of a gas-driven liquid pump, in accordance with a present embodiment.

FIG. 2 is a schematic, cross-sectional view along line II-II of FIG. 1, but showing a pumping pipe of the gas-driven liquid pump.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments will now be described, in detail, below with reference to the drawings.

FIG. 1 shows a gas-driven liquid pump 100 for removing liquids. The present gas-driven liquid pump 100 can be used to remove liquid waste during the manufacturing of printed circuit boards. The gas-driven liquid pump 100 includes a tank 10, a liquid conveying pipe 20, a gas source 30, a gas conveying pipe 31, and a pumping pipe 40. The gas source 30 is to generate pressurized gas. The pressurized gas can be transmitted to the pumping pipe 40 by the gas conveying tube 31. The tank 10 is provided for containing liquids. The liquid conveying pipe 20 is configured for feeding the liquids from the tank 10 to the pumping pipe 40.

In detail, one end of the liquid conveying pipe 20 is connected to the tank 10, and another end of the liquid conveying pipe 20 is connected to the pumping pipe 40. One end of the gas conveying pipe 31 is connected to the pumping pipe 40, and another end of the gas conveying pipe 31 is connected to the gas source 30. Advantageously, a valve (not shown) can be arranged on the gas conveying pipe 31 to control a pressure of the pressurized gas entering into the pumping pipe 40. Similarly, a valve (not shown) can be arranged on the liquid conveying pipe 20 to control the flow of the liquid from the tank 10 to the pumping pipe 40. It is to be understood that the liquid conveying pipe 20 and the gas conveying pipe 31 can be two or more pipes for transmitting liquid or gas, respectively.

The pumping pipe 40 includes a gas input pipe 41 and a liquid output pipe 42. The gas input pipe 41 includes a first end 411 and a second end 412. The gas input pipe 41 is tapered from the first end 411 to the second end 412. An inner diameter of the first end 411 is larger than that of the second end 412. That is to say, a cross-sectional area of the first end 411 is larger than that of the second end 412. The inner diameter of the gas input pipe 41 gradually decreases from the first end 411 to the second end 412. In other words, the cross-sectional area of the gas input pipe 41 gradually decreases from the first end 411 to the second end 412. The liquid output pipe 42 includes a third end 421 and a fourth end 422. An inner diameter of the liquid output pipe 42 gradually increases from the third end 421 to the fourth end 422. In other words, a cross-sectional area of the liquid output pipe 42 gradually increases from the third end 421 to the fourth end 422.

The first end 411 of the gas input pipe 41 mates with the gas conveying tube 31, with the pressurized gas entering the gas input pipe 41 therefrom. The second end 412 of the gas input pipe 41 mates with the third end 421 of the liquid output pipe 42. The second end 412 can be joined with the third end 421 by employing an adhesive or a mechanical means. Also, the pumping pipe 40 can have an integrated configuration. That is, the pumping pipe 40 can be configured as an integral unit without a joint between the gas input pipe 41 and the liquid output pipe 42. An inner diameter of the second end 412 of the gas input pipe 41 is equal to an inner diameter of the third end 421 of the liquid output pipe 42. The fourth end 422 is configured as an outlet for the liquid waste. In the present embodiment, this liquid waste is the liquid previously used to clean printed circuit boards.

In the present embodiment, the second end 412 of the gas input pipe 41 is directly connected to the third end 421 of the liquid output pipe 42. In addition, the second end 412 of the gas input pipe 41 can be indirectly connected to the third end 421 of the liquid output pipe 42. For example, a straight tube having uniform inner diameter can be arranged and structured for connecting the second end 412 of the gas input pipe 41 and the third end 421 of the liquid output pipe 42. Usefully, the inner diameter of the straight tube is identical with the inner diameters of the second end 412 and the third end 421. The gas input pipe 41 has a straight line axis, and the liquid output pipe 42 has a straight line axis. The straight line axis of the gas input pipe 41 and that of the liquid output pipe 42 are collinear. Due to such configuration, a viscosity resistance of the gas flowing in the pumping pipe 40 can be effectively reduced.

The inner diameter of the first end 411 of the gas input pipe 41 is identical with an inner diameter of the gas conveying pipe 31. As a result, the pressure of the gas conveyed in the gas conveying pipe 31 is equal to the pressure of the gas entering the first end 411 of the gas input pipe 41. As such, the gas, generated by the gas source 30, can be conveyed by the gas conveying pipe 31 to the first end 411, of the gas input pipe 41, with a stable pressure.

An end of the liquid conveying pipe 20 is coupled to a joint between the second end 412 of the gas input pipe 41 and the third end 421 of the liquid output pipe 42. The end of the liquid conveying pipe 20 can also be coupled to a position of the gas input pipe 41 or the liquid output pipe 42 close to the third end 421. Thus, the liquid from the tank 10 can flow into the pumping pipe 40. Advantageously, an axis of the liquid conveying pipe 20 intersects with the axis of the liquid output pipe 42 at an acute angle. The acute angle is in a range from about 30 degree to about 60 degree.

A working principle of the gas-driven liquid pump 100 is described in detail. According to principle of continuity of fluid, a product (Q: denoting a volume of a fluid flowing through a cross section of a pipe per second) of an area (A) of any cross section and a velocity (V) of a fluid flowing through corresponding cross section in a same pipe is a constant. Q, A and V are related by the equation: Q=A*V. According to the equation, the fluid velocity is faster in the smaller cross-sectional area than in larger cross-sectional area. That is, the cross-sectional area is inversely proportional to the velocity of a fluid flowing through the corresponding cross section of the pumping pipe 40. Because the cross-sectional area of the first end 411 is larger than that of the third end 421, the velocity of the pressurized gas flowing through the first end 411 is less than the velocity of the pressurized gas flowing through the third end 421.

In addition, velocity (V), pressure (P), density (ρ) of the fluid flowing in the pumping pipe 40 are related by the equation: P/ρ+V²/2=C, wherein C is a constant. For example, the pressure of the pressurized gas flowing through the first end 411 is denoted by P₁, the pressure of the pressurized gas flowing through the third end 421 is denoted by P₃, ρ is a constant, another equation can be deduced: P₃−P₁=V₁ ²−V₃ ². If V₁<V₃, then P₁>P₃. Because P₁ is determined by the gas generated by the gas source 30, P₁ can be adjusted, by the gas source 30, to any suitable value.

In the operation of the gas-driven liquid pump 100, the liquid in the tank 10 needs to be removed from the tank 10 into the third end 421 of the pumping pipe 40. Therefore, the pressure of the third end 421 (P₃) should be less than the pressure of the liquid in the tank 10. According to the above relationship of P₃ and P₁, it can be concluded that P₃ can be determined/adjusted by P₁. In detail, when the pressurized gas flows from the first end 411 to the third end 421 (i.e., the second end 412), the pressure of the pressurized gas gradually decreases from the first end 411 to the third end 421. According to such gradual decrease, if a value of P₁ is predetermined, after the pressurized gas moves to the third end 421, the value of P₁ can be decreased into a corresponding value of P₃. When the predetermined value of P₁ is equal to or less than the pressure of the liquid in the tank 10, the value of P₃ is evidently less than the pressure of the liquid in the tank 10. When the predetermined value of P₁ is larger than the pressure of the liquid in the tank 10, the value of P₃ will be less than the pressure of the liquid in the tank 10 due to the gradual decrease of the pressurized gas from the first end 411 to the third end 421. For example, the pressure of the liquid in the tank 10 is equal to one atmospheric pressure (P₀), and P₁ is also equal to P₀, thus P₃ is less than P₀. Thus the liquid of the tank 10 can be pressed into the pumping pipe 40 through the liquid conveying pipe 20. Subsequently, the liquid flowing in the pumping pipe 40 can flow out from the fourth end 422 of the liquid output pipe 42. In such fashion, the gas-driven liquid pump 100 removes the liquid in the tank 10.

According to above working principle of the gas-driven liquid pump 100, the parameters such as inner diameter of the pumping pipe 40 and the velocity of the fluid (e.g. pressurized gas) can affect the pressure of the pressurized gas flowing in the pumping pipe 40, thereby affecting the operation of the gas-driven liquid pump 100. Considering such parameters, an exemplary pumping pipe 40 is now provided. A length (L1) of the gas input pipe 41 is a vertical distance between the first end 411 and the second end 412. A length (L2) of the gas output pipe 42, i.e., a vertical distance between the third end 421 and the fourth end 422. L2 is from 1.5L1 to 2.5L1. The inner diameter (D1) of the first end 411 is from 0.5L1 to 0.7L1. The inner diameter (D2) of the second end 412 is equal to 0.3D1˜0.5D1, advantageously, equal to 0.4D1˜0.44D1. The inner diameter (D3) of the third end 421 is equal to D2. The inner diameter (D4) of the fourth end 422 is equal to 0.4L1˜0.5L1, i.e., equal to 0.71D1˜0.8D1. A liquid level height of the liquid of the tank 10 is denoted by H. L1 is equal to 0.25H˜0.5H. Therefore, the parameters of the gas-driven liquid pump 100 can be predetermined according to the liquid level height of the tank 10. More specifically, in practical application, e.g., in a process for clearing printed circuit boards, according to a predetermined drainage discharge (e.g., a liquid level height), the structure and dimension of the gas-driven liquid pump 100 can be determined. Thus, a desired gas-driven liquid pump 100 can be gained.

In a normal operation of the gas-driven liquid pump 100, the pressure of the pressurized gas generated by the gas source 30 is in a range from about one atmospheric pressure to five atmospheric pressure. Such pressurized gas enters the gas input pipe 41, the pressure thereof gradually decreases with the pressurized gas flowing from the first end 411 to the third end 421. When the pressurized gas flows to the third end 421 of the liquid output pipe 42, the pressure of the pressurized gas can become less than one atmospheric pressure. Because the pressure of the liquid in the tank 10 is equal to one atmospheric pressure, so a pressure difference can be formed between the third end 421 and the tank 10. As a result, the liquid of the tank 10 can be pushed into the pumping pipe 40 due to the presence of the pressure difference. Finally, the liquid of the tank 10 can be pumped out by the gas-driven liquid pump 100.

In the present embodiment, the liquid level height H is about 4 centimeters and an inner meter of the liquid conveying pipe 20 is about 2 millimeters. Hence, the length of the gas input pipe 41 and the liquid output pipe 42 is, respectively, about 12 millimeters and 23 millimeters. The inner diameter of the first end 411, the second end 412, the third end 421 and the fourth end 422 is, respectively, about 7.2 millimeters, 3 millimeters, 3 millimeters and 5.4 millimeters. The pressure of the pressurized gas through the first end 411 is adjusted to be 2.5 atmospheric pressure, when the pressurized gas flows to the third end 421, the pressure of the pressurized gas reduces to 0.5 atmospheric pressure. Therefore, the pressure of the third end 421 is less than that of the tank 10 (the pressure of the tank 10 is about one atmospheric pressure), so the liquid of the tank 10 can be forced into the pumping pipe 40. Thus, the liquid of the tank 10 can be pumped and drained out by the pumping pipe 40.

With respect to the present gas-driven liquid pump 100, the pumping pipe 40 can have an integrated structure. The pumping pipe 40 can be described in an alternative manner. That is, the pumping pipe 40 includes a gas input end (i.e., the first end 411), a liquid output end (i.e., the fourth end 422) and a suction portion (i.e., the second end 412 or the third end 421) located between the gas input end and the liquid output end. An inner diameter of the pumping pipe gradually decreases from the gas input end to the suction portion, and the inner diameter of the pumping pipe gradually increases from the suction portion to the liquid output end. At least one gas conveying pipe is configured for connecting the gas source and the gas input end of the pumping pipe. At least one liquid conveying pipe is configured for connecting the tank and the suction portion of the pumping pipe. For example, one end of the liquid conveying pipe is connected to the tank, and another end is engaged with the suction portion of the pumping pipe.

Compared with the conventional diaphragm pumps, the present gas-driven liquid pump 100 has a simple structure and a relative small size. The configuration of the pumping pipe can be applied in various drainage systems with various drainage discharges. Particularly, in the manufacturing process for wetting flexible printed circuit boards, the gas-driven liquid pump 100 can satisfy small amount of water pumping. In addition, the simple structure of the gas-driven liquid pump 100 can greatly save the space of the workshop.

It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention. 

1. A gas-driven liquid pump, comprising: a gas source; a tank; a pumping pipe comprising a gas input pipe and a liquid output pipe, the gas input pipe comprising a first end and a second end, an inner diameter of the gas input pipe gradually decreasing from the first end to the second end, the liquid output pipe comprising a third end and a fourth end, an inner diameter of the liquid output pipe gradually increasing from the third end to the fourth end, the second end being engaged with the third end, and the inner diameter of the second end being equal to the inner diameter of the third end; at least one gas conveying pipe configured for connecting the gas source and the first end of the gas input pipe; and at least one liquid conveying pipe, one end of the liquid conveying pipe being connected to the tank, and another end being engaged with the pumping pipe close to a joint between the gas input pipe and the liquid output pipe.
 2. The gas-driven liquid pumping apparatus as claimed in claim 1, wherein the joint is formed by the third end of the liquid output pipe and the second end of the gas input pipe.
 3. The gas-driven liquid pumping apparatus as claimed in claim 1, wherein an axis of the pumping pipe is a straight line, the liquid conveying pipe intersects with the axis at an acute angle.
 4. The gas-driven liquid pumping apparatus as claimed in claim 3, wherein the acute angle is in a range from about 30 degree to about 60 degree.
 5. The gas-driven liquid pumping apparatus as claimed in claim 1, wherein the pumping pipe has an integrated structure.
 6. The gas-driven liquid pumping apparatus as claimed in claim 1, wherein the second end of the gas input pipe is joined to the third end of the liquid output pipe by an adhesive.
 7. The gas-driven liquid pumping apparatus as claimed in claim 1, wherein the second end of the gas input pipe is mechanically joined with the third end of the liquid output pipe.
 8. The gas-driven liquid pumping apparatus as claimed in claim 1, wherein a length of the gas input pipe and liquid output pipe is respectively denoted by L1 and L2, a liquid level height of a liquid of the tank is denoted by H; L1 is in a range from about 0.25H to about 0.5H, L2 is in a range from about 1.5L1 to about 2.5L1.
 9. The gas-driven liquid pumping apparatus as claimed in claim 8, wherein the inner diameter of the first end, the second end, the third end and the fourth end is respectively denoted by D1, D2, D3 and D4; D1 is in a range from about 0.5L1 to about 0.7L1, D2 is in a range from about 0.3D1 to about 0.5D1, D3 is equal to D1, D4 is in a range from about 0.71D1 to about 0.8 D1.
 10. A gas-driven liquid pump, comprising: a gas source; a tank; a pumping pipe comprising a gas input end, a liquid output end and a suction portion located between the gas input end and the liquid output end, an inner diameter of the pumping pipe gradually decreasing from the gas input end to the suction portion, and the inner diameter of the pumping pipe gradually increasing from the suction portion to the liquid output end; at least one gas conveying pipe configured for connecting the gas source and the gas input end of the pumping pipe; and at least one liquid conveying pipe, one end of the liquid conveying pipe being connected to the tank, and another end being engaged with the suction portion of the pumping pipe.
 11. The gas-driven liquid pumping apparatus as claimed in claim 11, wherein an axis of the pumping pipe is a straight line, the liquid conveying pipe intersects with the axis at an acute angle.
 12. The gas-driven liquid pumping apparatus as claimed in claim 11, wherein the acute angle is in a range from about 30 degree to about 60 degree. 